MXPA02002165A

MXPA02002165A - Absorbent article having superabsorbent in discrete pockets on a stretchable substrate.

Info

Publication number: MXPA02002165A
Application number: MXPA02002165A
Authority: MX
Inventors: Richard Warren Tanzer
Original assignee: Kimberly Clark Co
Priority date: 1999-08-27
Filing date: 2000-08-22
Publication date: 2002-09-18
Also published as: US6610900B1; JP2003523791A; KR100695851B1; EP1225857B1; WO2001015646A1; EP1225857A1; JP4599014B2; PL366097A1; AU6924600A; KR20020022113A; DE60041590D1

Abstract

An absorbent article includes a liquid permeable top sheet, a substantially liquid impermeable, preferably water vapor permeable back sheet, and a selectively stretchable absorbent composite between the top sheet and the back sheet. The selectively stretchable absorbent composite is more stretchable in a first direction than in a second direction perpendicular to the first direction, and can be stretched to at least 150 % of an initial length in the first direction. The absorbent composite includes a selectively stretchable substrate layer and a plurality of pockets in or on the substrate layer. The pockets each contain a quantity of superabsorbent material, which can swell when exposed to a liquid insult. When the substrate is stretched, the pockets become spaced further apart, thereby promoting comfort and alleviating gel blocking caused by adjacent pockets swelling toward each other.

Description

- 1 ABSORBENT ARTICLE THAT HAS SUPERABSORBENT IN BAGS DISCRETS IN A STRETCHABLE SUBTRACT FIELD OF THE INVENTION 5 This invention relates to an absorbent article in which a superabsorbent material is contained in discrete bags in a selectively stretchable substrate. The bags can be found in one or more layers. When the material 10 superabsorbent gets wet, the resulting expansion causes adjacent bags to make contact and press on each other. The selectively stretchable substrate allows the expandable bags to be pushed and separated from each other in selected directions. Moreover, when the absorbent layer is 15 stretches in the selected direction the bags separate more from each other.

BACKGROUND OF THE INVENTION The absorbent composites suitable for use in disposable absorbent garments such as diapers, incontinent adult products, and the like are known. Such absorbent compounds are described, for example, in U.S. Patent 4,699,619 issued 25 October 13, 1987 to Bernardin, in the United States of America patent 4,798,603 granted on January 17, 1989 to Meyer et al., In the patent of the United States of America 4,834,735 granted on May 30, 1989 to Alemany et al., In United States of America patent 5,147,343 issued September 15, 1992 to Kellenberger, and in United States of America patent 5,149,335 issued September 22, 1992; 1992 to Kellenberger and others.

Generally such absorbent composites consist of a matrix to contain a high absorption material and a high absorption material. Suitable matrices for containing the high absorption material include fibrous matrices, such as those formed by air-laid cellulosic fibers or a coform material comprising cellulosic fibers and meltblown polyolefin fibers. A wide variety of high absorption materials (also known as superabsorbent materials) is known among those skilled in the art. See, for example, US Pat. No. 4,076,663 issued February 28, 1978 to Masuda et al., United States of America Patent 4,286,082 issued August 25, 1981 to Tsubakimoto et al., 4,062,817 issued in December 13, 1977 to Westerman, and United States of America Patent 4,340,706 issued July 20, 1982 to Obayashi et al.

Many known absorbent compounds consisting of a high absorption material employ the high absorption material at relatively low concentrations. That is, many of the absorbent compounds are composed of fibers i < AÁ, Si? F < i .; «T-jb.it a_Aia. "frlfil" i cellulosics placed with air and less than about 20 percent by weight of high absorption material. This is due to various factors.

Many high absorption materials are unable to absorb liquids as fast as liquids are applied to absorbent compounds during their use. Accordingly, it is desirable that a high relative concentration of fibrous material is desirable so that it temporarily retains the liquid until the high absorption material can absorb it. Moreover, the fibers serve to separate the particles of high absorption material so that gel blocking does not occur. Gel blocking refers to the situation in which particles of high absorption material deform in the process of swelling and block the spaces between the particles, or between the particles and fibers, thus preventing the flow of liquid between the particles. interstitial spaces.

The presence of a relatively low concentration of high absorption material and a relatively higher concentration of fibrous materials has resulted in the production of absorbent compounds that tend to be relatively thick. In some cases, the use of a relatively thick absorbent compound in a disposable absorbent garment is acceptable. However, in recent years it has become more desirable to produce absorbent compounds that are lighter in comparison with the more absorbent compounds. traditional but still have the same absorption capacity. The desire to produce relatively light absorption compounds has resulted in the desire to incorporate even more amounts of high absorption material into the absorbent composites. This is because the absorption capacity of such high absorption materials is generally many times greater than the absorption capacity of fibrous materials. For example, a fibrous matrix of wood pulp fluff can absorb around 7 to 9 grams of liquid, (like 0.9 percent by weight of salt water) per gram of wood pulp fluff, while high absorption materials they can absorb at least about 15, preferably at least about 20, and very frequently at least about 25 grams of liquid, such as 0.9 weight percent salt water per gram of high absorption material.

The trend toward more elastic diapers is illustrated in United States of America patent 5,846,232 issued to Serbiak et al., And in United States of America patent 5,451,219 issued to Suzuki et al. These references reveal several elastic or extensible structures in the diapers to achieve elasticity.

U.S. Patent 5,601,542 issued to Melius et al. Discloses an absorbent article in which the superabsorbent material is contained in layers of discrete bags. The bags are adjacent to each other others and are formed in one or more layer substrates. When the superabsorbent material gets wet, the substrates either do not stretch or stretch uncontrolled in all directions. In the first case, the absorption capacity of the superabsorbent can be inhibited by the external pressure applied to the substrates that work against the expanding pressure of the superabsorbent. In the second case, the uncontrolled way of stretching can cause the wet superabsorbent gel to be modified, reducing the effectiveness of the absorption system and causing discomfort for the user.

SYNTHESIS OF THE INVENTION The present invention is an absorbent article having an absorbent composite that is selectively stretchable in one direction, wherein the superabsorbent material is present in discrete bags or packages in or on stretchable selective substrates. The absorbent article includes at least one back sheet substantially impervious to liquid and vapor permeable, a liquid pervious top sheet placed in a front facing relationship to the backsheet, and one or more of the selectively stretchable layers between the top sheet and the backing sheet. later.

The substrate in the absorbent composite is selectively stretchable in one direction. For example, the substrate in a diaper product can stretch laterally .- ^ ..-. J- ^ mu, * between the legs of the user, without stretching longitudinally in the regions of the user's waist. In one embodiment, the substrate may be a laminate of a non-elastic filament fabric of narrowed fabric and attached to an elastic film. Narrow and joined laminates of this type are described in United States of America Patent 5,883,028 issued to Morman et al., The texts of which are incorporated by reference. Other applicable substrates include, without limitation, spun-bonded and narrowed fabrics and spun-bonded and creped fabrics.

In one embodiment, the selectively stretchable substrate may contain two layers of material that are joined together to form a plurality of pockets therebetween. The bags can be formed in one or both layers. At least one of the layers must be permeable to water. The other layer may be permeable to water or not permeable to water. The absorbent composite may also contain two of the selectively stretchable substrates, bonded with a plurality of pockets therebetween. In any case, the superabsorbent material is located in the bags.

During use of the absorbent article, the bags maintain the desired distribution of the superabsorbent material in the absorbent composite. The selectively stretchable substrate allows for stretching of the absorbent layer in the desired direction, to accommodate user movement as well as swelling of the superabsorbent when it is wetted. The absorbent composite can be used in a wide variety of absorbent articles including, for example, absorbent personal care products and absorbent medical products. Absorbent personal care products include diapers, underpants, swimwear, absorbent underpants, baby wipes, adult incontinence garments, and women's sanitary products. Medical absorbent products include absorbent garments, pads, bandages, absorbent covers and medical wipes.

With the foregoing in mind, it is a feature and an advantage of the invention to provide an absorbent article having a relatively stretchable absorbent composition and a distribution of products containing superabsorbent material to lighten gel blocking.

It is also a feature and an advantage of the invention to provide an absorbent article having a selectively stretchable absorbent composite that is preferably stretched in the desired direction.

The foregoing and other features and advantages will become apparent from the following detailed description of the currently preferred embodiments. The detailed description is illustrative rather than limiting of the scope of the invention ... tf r i.Áía¡ - ^^^ í ^ .-. ^ .-- ':: ^: Í. ^^^' fF. ^, - ít "ttta As-t-fe ..., which is defined with the appended claims and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic perspective view of an incorporation of an absorbent article according to the present invention, which is a disposable diaper.

Figure 2 shows a plan view in section of an absorbent compound useful in the article of Figure 1.

Figures 3, 3A and 3B schematically illustrate the formation of a tapered and bonded laminate useful as a substrate in the absorbent composite.

DETAILED DESCRIPTION OF THE PREFERRED INCORPORATIONS PRESENT The present invention is an absorbent article having an absorbent composite layer that is selectively stretchable, wherein the superabsorbent material is present in discrete pockets or receptacles within or on selectively stretchable substrates. The term "absorbent article" includes, without limitation, diapers, training briefs, swimwear, absorbent briefs, baby wipes, adult incontinence products, women's sanitary products, and absorbent medical products (eg, medical clothing) absorbent, pads, bandages, covers and medical wipes).

A preferred absorbent article is a disposable diaper. Figure 1 illustrates a schematic perspective view of a disposable diaper according to an embodiment of the present invention having a longitudinal direction 1 and a lateral direction 2. The disposable diaper 10 includes an outer cover 12, a body side liner 14 , and an absorbent compound 44 located between the body side liner 14 and the outer cover 12. The absorbent compound 44 consists of a plurality of bags 50 containing the superabsorbent material 58 and, optionally, wood pulp fibers as described further ahead . The absorbent composite also includes a two-piece wrapping sheet composed of a first layer of substrate sheet 46 and a second substrate layer 48 which is described below. The two-piece wrapping sheet extends to the edges of the absorbent composite 44 and beyond the bags 50, to define the perimeter 24 that can be sealed to prevent the superabsorbent material 58 from moving out of the diaper.

Subjects between the outer cover 12 and the lining of the body side 14 are the waist elastics 26, the fastening tapes 28 and the leg elastics 30. ii = leg elastics 30 consist of a carrier sheet 32 and individual elastic threads 34 having the near edges 19 and the distant edges 21.

Attached to the liner on the body side 14 are the containment fins 36 having the near edges 38 and the distant edges 40. The near edges of the leg elastics correspond to the distant edges of the containment fins. An emergence management layer 42 having the perimeter 43 is located between the near edges 38 and the containment fins 36.

Many of the exact construction methods and diaper materials illustrated in Figure 1 are more fully detailed in commonly assigned U.S. Patent 5,509,915 issued April 25, 1996 in the name of Hanson et al., And in the patent. of the United States of America 5,904,675 granted on May 19, 1999 to Laux and others, both of which have been incorporated herein by reference. Possible modifications to the diaper illustrated in Figure 1 include the positioning of the emergence management layer 42 between the body side liner 14 and the absorbent composite 44 and reducing the length of the emergence management layer to extend the length of the absorbent compound, or (reduce the length and increase the basic weight) the emergence management layer in the diaper area in ^ á & F.,. ^. ^. J., ^^^ F ^^,. ^. ^ ^ ^ ^ F ^^ - k ^^ m where the excess liquid initially accumulates (target zone).

Figure 2 illustrates a selectively stretchable absorbent composite in accordance with this invention. With reference to Figure 2 the absorbent composite 44 comprises a first layer of liquid permeable and selectively stretchable substrate 46 and bags 50 of the superabsorbent material formed between the first layer 46 and a second layer 48.

As used herein, the term "selectively stretchable" means that a material is more stretchable in a first direction than in a second direction, that is, it can be stretched to a greater degree without breaking in the first direction than in the second direction. . The second direction is perpendicular to the first direction. Generally, the material is stretchable to at least 150% of its initial length in the first direction, conveniently up to at least 200% of its initial length in the first direction, desirably up to at least 250% of its initial length in the first direction . Generally, the material is stretchable to less than 140% of its initial length in the second direction, suitably less than 125% of its initial length in the second direction, desirably less than 110% of its initial length in the second direction.

The bags 50 are defined through the fastening means 52 which serve to operatively connect the first and second layers to form a laminate and to maintain the integrity of the laminate when the laminate is dry but to release them controlled when the laminate is wetted. Alternatively, the bags 50 can be molded (e.g., thermoformed) into a layer 46 or a layer 48. Convenient securing means between the layers 46 and 48 include a water sensitive adhesive, such as water soluble adhesives and the like. thermal engraving. The fastening means 52 secures the first layer 46 and the second layer 48 to provide bonded areas 54 between the bags 50, and unbonded areas 56 in the bags 50. The unbonded areas help define the bags 50. A superabsorbent material 58 it is located in the bags 50 to provide the absorbent compound 44. In addition to the absorbent material 58, the bags 50 may contain a fibrous material such as cellulose fluff or other material, as noted below. Secondary fastening means (not shown) that are insensitive to water can also be used to secure the layers 46 and 48 together at spaced locations of the bags 50.

The bags 50 are spaced apart by a distance 60 when the compound 44 is at rest, that is, it is not subject to stretching forces. Space 60 is at least about 0.05 inches (1.3 millimeters), alternately at least about 0.10 inches (2.5 millimeters) or alternatively at least 0.15 inches (3.8 millimeters). Moreover, the space of the bags 60 is conveniently no greater than 1.5 inches (38 millimeters), alternatively no greater than 1.0 inches (25 millimeters), or alternatively no greater than 0.5 inches (13 millimeters).

The depth of the bags 50 can be at least 0.1 inches (2.5 millimeters), preferably 0.15-0.50 inches (3.8-13 millimeters), more preferably 0.20-0.30 inches (5.1-7.6 millimeters). The bags may have a circular or elliptical configuration, with diameters ranging between 0.20 and 1.0 inches (5.1 and 25 millimeters), preferably 0.25 to 0.75 inches (6.4 to 19.1 millimeters), more preferably 0.40 to 0.60 inches (10.2 to 15.2). millimeters). These dimensions refer to the state at rest without stretching of the absorbent compound 44.

According to the invention, the absorbent composite 44 should be stretchable in a first direction, and not stretchable in a second direction perpendicular to the first direction. "Stretchable" means that compound 44 is stretched at least 150% of its initial length in the first direction without breaking, preferably up to at least 200% of its initial length, more preferably up to 250% of its initial length. Preferably, the absorbent composite is at least partially retractable in the direction opposite to the direction of stretching. So, when the force that causes the . "_to ? - ^ - a- ^ e. -. ^ j, tiaií ^^? * s ^^^^^ > As the stretch becomes loose, the stretchable composite should recover or "retract" at least 25%, preferably up to 50%, more preferably up to 75%. A "50% recovery" for example, means that when the material is stretched from its initial length of one meter to a stretched length of two meters, it should be recovered to a length of 1.5 meters when the stretching force stops. The stretchability of the absorbent composite 44 is generally controlled by the stretchability of the combined layer or substrate layers 46 and 48.

The absorbent composite 44 should be less stretchable in a second direction that is perpendicular to the first direction. By "non-stretchable" or "less stretchable", it is meant that compound 44 is stretched at least 150% of its initial length in the second direction before breaking, preferably to less than 125% of its initial length, and more preferably less than 110% of its initial length.

Certain materials, for example, lightly bonded non-woven materials, do not necessarily have a breaking point when stretched. The force required to lengthen such materials increases to the maximum and gradually decreases as the elongation continues, before it abruptly drops to zero when the material breaks. Such behavior can be characterized as "marshmallow type". »3. ^ i £ S ^. As certain non-woven materials are stretched, the fibers change and gradually orient themselves in the direction in which the material is pulled. As the stretch continues, the fibers can come out of the non-woven matrix gradually reducing the force required to reach more stretch.

Absorbent compounds that exhibit marshmallow behavior in a first direction do not necessarily exhibit the same marshmallow behavior in a second direction perpendicular to the first direction.

By "stretchable" absorbent compounds that exhibit marshmallow behavior in at least one direction is meant that the maximum force required to stretch compound 44 to 150% of their initial length is less than the maximum force required to stretch it in a direction perpendicular to 125% of its initial length. Preferably, the maximum force required to stretch the compound to 200% of its original length is less than the maximum force required to stretch it in a direction perpendicular to 125% of its initial length. More preferably the maximum force required to stretch the composite to 250% of its original length is less than the maximum force required to stretch it perpendicular to 125% of its initial length. Í? Correspondingly, by "non-stretchable" compound exhibiting marshmallow behavior in at least one direction means that the maximum force required to stretch compound 44 at 150% of its initial length is at least equal to the maximum force required to stretch it perpendicularly to 125% of its initial length.

The strain and tensile strain measurements required to determine the forces on these marshmallow-type compounds will be handled using International standards ISO 1924-2: 1994 (E), Paper and Cardboard - Determination of tensile properties -Part 2: Constant rate elasticity method, or similar methods.

The absorbent compound 44 is oriented in the absorbent article so that the direction of the selective stretch corresponds to the direction in which the article can be desirably stretched. In a diaper for example, the preferred stretch direction may be lateral from one leg to the other of the wearer. This allows the user to move their legs freely without experiencing discomfort. In this instance, the preferred direction of no stretch, or less stretch, may be from front to back, between the user's waist areas. Alternatively, a diaper can be configured in such a way that longitudinal stretching of the absorbent is preferred. To provide a better fit for For example, a diaper may stretch gently in the longitudinal direction to conform to the baby.

Figures 3, 3A and 3B schematically illustrate the formation of a tapered and bonded laminate that can be employed as the first layer of the substrate 46 and / or the second substrate layer 48 of the absorbent compound 44. Figure 3 illustrates the narrowable material 112 that it can be for example a fibrous nonwoven fabric made of a relatively non-elastic polymer material. With reference to Figure 3B the stretchable material 112 is first pulled in the machine direction, causing its fibers to be oriented longitudinally and causing its length in the opposite direction to contract from a first dimension A to a second dimension B. At that point , the non-woven non-woven fabric 112 is laminated to a non-stretchable elastic film or other layer of material, for example using the techniques described in U.S. Patent 5,883,028 to Morman et al., which is incorporated by reference. The term "elastic" refers to stretchable material that recovers largely to its initial length when the stretching forces are loosened.

The resultant laminate 114, shown in Figure 3B, has a relaxed length in the machine direction which is essentially equal to the dimension B. The laminate can be selectively stretched only in the transverse direction íi. *** tihim? t- ..? S? S? M,. »« * A ,. **, ** > ., A ^ t ^^^^^ _ i¿aia-fciij-J .. & i ^ «ifc-s AÉI.? the fabric machine 112, towards a second length essentially equal to the dimension A. When the stretching force is relaxed, the laminate 114 retracts to its original dimension A.

The narrowable fabric 112 can be a porous nonwoven material such as, for example, a yarn-bonded fabric, a meltblown fabric, bonded and bonded fabric. If the narrowable material is a fabric of blown fibers with melting, this may include meltblown microfibers. The narrowable material 112 can be made of fiber-forming polymers such as, for example, polyolefins. Examples of polyolefins include one or more of polypropylenes, polyethylenes, ethylene copolymers, propylene copolymers and butene copolymers. Useful polypropylenes include, for example, the polypropylenes available from Exxon Chemical Company under the trade designation Exxon 3445, and the available polypropylenes from the Shell Chemical Company under the trade designation DX5A09.

The narrowable fabric 112 can be a multilayer material having for example at least one layer of fabric spun-bonded with at least one layer of meltblown fabric, a carded and bonded fabric or any other suitable material. For example, the narrowable material 112 can be a multilayer material having a first layer of polypropylene bonded with yarn having a basis weight of about 0.2 to 8 ounces per square yard (osy) (about 6.8 to 270 grams per square meter, or gsm), a melt blown polypropylene layer that has a basis weight of about 0.2 to 4 ounces per square yard (6.8 a 135 grams per square meter), and a second layer of polypropylene bonded with yarn that has a basis weight of around 0.2 to 8 ounces per square yard (6.8 to 270 grams per square meter). Alternatively, the narrowable fabric 112 may be a single layer of material such as, for example, a spun fabric having a basis weight of about 0.2 to 10 ounces per square yard (6.8 to 340 grams per square meter) or a blown fabric with Fusion that has a basic weight of around 0.2 to 8 ounces per square yard (6.8 to 270 grams per square meter). The contiguous fibers of the fabric 112 should be intermittently joined by bonding between fibers, using conventional industry techniques.

An elastic sheet can be attached to the narrowable fabric 112 when the latter is in a tensioned and tapered state to form a bonded and bound laminate 114. The elastic sheet can be made of water vapor permeable elastic polymer, or it can be made of another elastic polymer and make it permeable to vapor forming openings or micropores in the sheet. Preferably, the elastic sheet has a moisture vapor transmission rate (MVTR) of about 500 grams per square meter per 24 hours, more preferably about 1200 grams per square meter per 24 hours, and more preferably around 2000 grams per square meter for 24 hours using the test procedure described below. The moisture vapor transmission rate is a function of the thickness of the film and the type of the polymer. Elastic polymers that exhibit the required vapor transmission rate over a useful range of film thicknesses include without limitation vulcanized silicone rubber, other silicone polymers, polyurethanes, polyether esters and polyether amides. The following Table 1 represents the permeability of the water vapor of the elastic polymer specimens, standardized to justify the thickness of the film of a pure polymer film. Table 1 If the elastic polymer has a low vapor permeability, the film can be extremely to? i áAA- f- »> -i * i ffc. «.J - ^ ...... • - flff * ft • - * &? Neb? Tt £ iu¡aiJbF *? ~ F¿.? BB > * "- '? Ad - * f-iii -'" t '' a '- - t thin to achieve the desirable minimum level of moisture vapor transmission rate Elastomers having a lower vapor permeability Moisture include, for example, styrene-butadiene copolymers and terpolymers, elastomeric ethylene-propylene copolymers, ethylene-propylene diene rubbers, and certain metallocene-catalyzed or single-site ethylene polymers and ethylene alpha olefin copolymers having a density not greater than 0.89. Alternatively, the film can be made porous or microporous using the many techniques familiar to people skilled in the art.The production and use of very thin films may be impractical due to the low strength of the film and the difficulties in the process.The elastic polymer itself should therefore have sufficient moisture vapor permeability to allow the use of films with thick p Preferably, the elastic polymer will have a water vapor permeability of at least 150 kilograms per square centimeter (square kilometer) per day, and more preferably around 500 kilograms per square centimeter per square kilometer per day, and more preferably around 1000 kilograms per square centimeter (square kilometer) per day.

In addition to being permeable to water vapor, the preferred elastic film capable of breathing should not be so thick as to substantially prevent vapor transmission water ikdJU. The moisture vapor transmission rate of a particular film composition is approximately inversely related to its thickness if there are no molecular interactions between the film and the vapor. For water vapor permeable films this relationship may vary due to the affinity of the water with these films. Generally, the elastic film composing the tapered and bonded laminate 114 should be less than 2 mils (50 microns) thick, preferably less than about 1 mil (25 microns) thick, more preferably less than 0.5 mils (13 microns) thick, when the film and laminate 114 are at rest.

With reference to Figure 2, when the bonded or bonded laminate is used as a substrate in the absorbent composite 44, the upper layer 46 (liquid permeable), which faces the wearer, can be a non-woven, tapered layer and the lower layer 48 may be a film or elastic sheet of the laminate that is narrowed and joined together. Alternatively, the lower layer 48 may include a narrowed and joined whole laminate (film and narrowed non-woven fabric), and the top layer 46 may be another non-woven layer or another liquid-permeable layer, such as a layer of material bonded with non-woven yarn. Layers 46 and 48 can be joined together using a wide variety of conventional techniques, including adhesive, thermal, ultrasonic bonding and the like. Preferably, the bonding area constitutes about 10 to 20% of the inter face between the layers 46 and 48. In a preferred embodiment, a heat melt stretchable adhesive 25 or 25A available from the Findley Adhesives Company is applied in a pattern. of turning covering 10 to 20% of the between face.

The bags 50 can be formed in the layer 46 or in the layer 48 and are preferably formed in the lower layer 48. The bags 50 can be formed using a thermoforming suction process or other suitable process. In an incorporation, the formation of bags, the application of superabsorbent and the union are carried out in the integration process. Initially, a selected stretchable material 46 such as the spunbonded and narrowed material is placed on the perforated plate having depressions in the shape of the bags. The vacuum is applied to the plate, causing the material to be pulled into the depressions in the shape of pockets. A superabsorbent is added to each bag and an adhesive is applied to the layer 46. Then the upper layer 48, which is permeable to the liquid is placed on the layer 46 and its bags and is pressed. The layers 46 and 48 are thus joined by the action of the adhesive.

In another embodiment, one of the substrate layers 46 or 48 can be removed. If the layer of the substrate 46 is removed, the liquid-permeable body-side liner 14 can act as an upper layer of the substrate in connection with the substrate of the layer 48. If the layer of the substrate 48 is removed, the outer layer 12 is waterproof to the liquid can % »± ?? ?. *. ÜÉ? * H ^ MíL¿ .... fr! Ftfflfc ^ - «^ - > »- -? -» - »- rf * act as the substrate of the lower layer in conjunction with the substrate of the layer 46. If the body side liner 14 or the outer cover 12 is used as a substrate, then it is it should selectively stretch it as described here for the substrate layers.

The term "superabsorbent" or "superabsorbent material" refers to an organic or inorganic material insoluble in water and swellable in water, able to absorb under the most favorable conditions at least 20 times its weight and more desirably at least 30 times its weight in an aqueous solution containing 0.9 weight percent of sodium chloride. The Standard Test Method IST 10.1 (95), "Standard Test Method for Absorption Time, Absorption Capacity and Transmission Time", published by the INDA, Association of the Non-Woven Materials Industry, Cary, Carolina North, provides the basis for the method of an adequate test on the measurement of absorption. The Test for "Absorbance Capacity (of small samples)" can be used to determine the absorption of a material for the purpose of this invention, with the following two modifications: i) IST 10.1 (95) specifies that water should be used , replace with an aqueous solution of 0.9%, ii) IST 10.1 (95) specifies that a sample of 5 grams be used. If necessary, a smaller sample, obtained from an absorbent product, can be used.

The superabsorbent materials can be natural, synthetic or modified natural materials and polymers and materials. Additionally, the superabsorbent materials may be inorganic materials, such as silicon gel, or organic compounds such as cross-linked polymers. The term "crosslinked" refers to any means for rendering the water-soluble materials essentially insoluble but swellable in water. Such means may include, for example, entangled physical entanglement, crystalline domain, covalent binding, complexes and ionic associations, hydrophilic associations, such as hydrogen bonding and hydrophobic associations of Van der Waals forces.

Examples of polymers of synthetic superabsorbent materials include the alkali metal and the ammonium salts of polyacrylic acid and polymethacrylic acid, polyacrylamides, polyvinyl ethers, maleic anhydride copolymers with vinyl ethers and alphadefins, polyvinyl pyrrolidones, polyvinyl morpholinones, polyvinyl alcohol and mixtures and copolymers. Other superabsorbent materials include modified natural and natural polymers, such as hydrolyzed acrylonitrile starch, grafted starch of acrylic acid, methyl cellulose, chitosan, carboxymethyl cellulose, hydroxypropyl cellulose, and natural gums such as alginates, xanthan gum, locust bean gum, and the like. Í? * J »-.- VtSü * u. • -.-. *. i.

Mixtures of natural or fully or partially synthetic superabsorbent polymers may also be useful in this invention. Other useful absorbent gelation materials are described by Assarsson et al. In United States of America patent 3,901,236 issued August 26, 1975. Processes for preparing synthetic absorbent gelation polymers are described in US Pat. America 4,706,663 granted on February 28, 1978 to Masuda and others and in the United States of America patent 4, 286,082 granted on August 25, 1981 to Tsubakimoto et al.

The superabsorbents can be particulate or fibrous and are preferably particulate. The superabsorbents are generally available in particles whose sizes are between about 20 to 1000 microns. The particles are preferably within the size range of 100 to 1000 microns. Examples of commercially available superabsorbent particles include SANWET® IM 3900 and SANWET® IM 5000P, available from Hoescht Celanese located in Portsmouth, Virginia, DRYTECH® 2035LD available from Dow Chemical Co located in Midland, Michigan, and FAVOR® 880 available from Stockhausen, located in Sweden. FAVOR® 880 is currently preferred by the great strength of its gel. An example of a fibrous superabsorbent is OASIS® 101 available from Technical Absorbents located in Grimsby, United Kingdom.

Depending on the size of the bags 50, and the density of the superabsorbent, each bag may contain about 25 to 500 milligrams of superabsorbent material, based on its dry weight, preferably about 50 to 300 milligrams, more preferably about 100 to 200 milligrams. . The number and size of the bags 50 may be such that the selected stretchable absorbent composite 44 contains from 1 to 100 grams of the total superabsorbent, preferably about 3 to 50 grams, and better still about 5 to 15 grams. Of course, the total amount of the superabsorbent can vary depending on the size of the absorbent article. Moreover, more than one selected selectively absorbent absorbent composite 44 may be present in the absorbent article, and two or more selected stretchable absorbent compounds 44 may overlap one over the other.

In addition to the superabsorbent material, each bag 50 may contain, if desired, a fibrous absorbent material such as pulp fibers, filler material, odor absorbing material, fragrant material, or any other suitable material. When the combination of materials is used, the superabsorbent should constitute at least 30% of the total material in the bags 50, preferably at least 50%, and better still at least 70%, much better at least 90% . Alternatively, some of the bags, preferably less than 50% may not contain superabsorbent. The bags without superabsorbent may contain only odor absorbing materials, fragrances, lotions, emollients, antimicrobials and the like.

The selected stretch of the absorbent compound 44 allows a high concentration of superabsorbent to be contained in the bags 50, without gel blockage occurring when the compound is wetted. As the superabsorbent gets wet and the bags expand towards each of them, the selected stretch of compound 44 allows the movement of the bags, thus preventing their contact from being so tight that it is from a gel block.

Preferably, the bags 50 have a shape that allows them to touch each other without closing all spaces between them. When seen in the project, as in Figure 2, the bags 50 have circular, oval, or elliptical shapes. Bags with these shapes are also less prone to rupture under the forces of superabsorbent swelling and stretching, and of the forces applied during the production process. Square and rectangular shapes are less preferred, because these shapes can substantially allow continuous contact along the edges of adjacent bags 50. Likewise, bags with these shapes are more susceptible to rupture under pressure.

The absorbent composite 44 can be added to the outer cover 12 and the lining of the body side 14 (FIG. 1) using a variety of techniques including thermal bonding, ultrasonic bonding, mechanical stitch bonding, adhesive bonding and the like. In order to achieve optimum performance, it is desirable that the preferred stretch of the absorbent composite 44 be allowed to control the stretching of the entire diaper 10. This can be accomplished by forming the other layers of the diaper 10 of materials that are at least as stretchable as the absorbent composite 44. The body side liner 14 and the outer cover 12 need not be selectively stretchable. They can be stretched uniformly in all directions and can be formed using one or more of the elastic polymers described above. While the materials forming the layers 12 and 14 (and any other layer) are at least as stretchable as the absorbent compound 44, all of the diaper 10 will have selective stretch influenced by the absorbent compound 14.

Both the emergence layer 42 and the body side liner 14 are constructed of highly liquid permeable materials. These layers function to transfer liquids from the user to the absorbent compound 44. Suitable materials include porous woven materials, porous nonwoven materials, and apertured films. Examples include without limitation any porous stretchable sheet of polymer fibers, carded fabrics of synthetic or natural fibers or a combination thereof. Any layer can also be a stretchable plastic film with openings.

The outer cover 12 may include a single stretchable layer or may include several stretchable layers bonded together by adhesive, ultrasonically bonded, thermally bonded or the like. The outer cover 12 can be made from a wide variety of woven and non-woven materials, films or films covered by non-woven materials, including for example blown or molded films. The outer cover 12 can also be a composite of carded, spun or blown materials, for example a composite of meltblown thermoplastic material or a meltblown thermoplastic material, while the spunbond layer can provide a fabric texture. and the melt blown layer can provide liquid impermeability. The outer cover 12 preferably has a high capacity for breathing with respect to water vapor.

Test Procedure to Measure the Humidity Vapor Transmission Rate (MVTR) One measure that a fabric is capable of breathing is the moisture vapor transmission rate (MVTR) that for sample materials is calculated essentially in accordance with the American Society for Testing and Materials (ASTM) Standard E96-80 with less variations in the test procedures as indicated below. Circular samples measuring three inches in diameter are cut from each tissue under test and are tested together with a control that is a piece of a CELGARD® 2500 sheet from the Charlotte Celanese Separation Products, North Carolina. The CELGARD® 2500 sheet is a microporous polypropylene sheet. Three samples are prepared for each tissue. The test dish is a number 60-1 Vapometer distributed by the Thwing-Albert Instrument Company of Philadelphia, Pennsylvania. One hundred millimeters of water are emptied into each dish of the Vapometer and the individual samples of the test weaves and the control material are placed on top of the dishes. Collars are bolted to seal the edges of the plate, leaving the test materials and control material exposed to the ambient atmosphere over a circle with a diameter of 6.5 centimeters that has an exposed area of approximately 33.17 square centimeters. The plates are placed in an air force oven at 100 degrees Fahrenheit (32 ° C) for one hour to balance. The oven is a constant temperature oven with external air circulating through it to prevent the accumulation of steam inside. A suitable air oven is for example the Blue M Power-O-Matic 60 oven distributed by the Blue M Electric Company of Blue Island, Illinois. When the balance is complete, the plates are removed from the oven, weighed and immediately returned to the oven. After 24 hours, the plates are removed from the oven and weighed again. The preliminary values of the vapor transmission rate test are calculated as follows: Moisture Vapor Transmission Rate = (weight in grams lost in 24 hours) x 315.5 grams per square meter-24 hours. The relative humidity in the oven is not specifically controlled. 5 Under predetermined conditions of 100 degrees Fahrenheit (32 ° C) and a relative humidity environment, the moisture vapor transmission rate for the CELGARD® 2500 control has been defined at 5000 grams per square meter in 24 hours. For this reason, the control sample is made with each test and the preliminary values of the test are corrected for the established conditions using the following equation: Humidity Vapor Transmission Rate = (Test 15 of Humidity Vapor Transmission Rate / Control of Humidity Vapor Transmission Rate) x (5000 grams per square meter-24 hours) Although the embodiments detailed herein are considered preferable, various modifications and improvements may be made without departing from the spirit and scope of the invention. The scope of the invention is indicated in the appended claims and all modifications that fall within the meaning and range of equivalence are intended to be included therein. $ ér X $ .. i? A .A ± ?? toá ???? I * L-t-h-É -.--. "- ^ 'fTr - *» - -y

Claims

R E I V I N D I C A C I O N S

1. An absorbent compound comprising: a selectively stretchable substrate which can be stretched to a greater extent in a first direction, and to a smaller extent in a second direction perpendicular to the first direction; a plurality of bags in or on the substrate material; Y a superabsorbent material in the bags; wherein the absorbent composite can be stretched to at least 150% of an initial length in the first direction, and only to less than 150% of an initial length in the second direction.

2. The absorbent compound as claimed in clause 1, characterized in that the composite can be stretched to at least 200% of the initial length in the first direction.

3. The absorbent compound as claimed in clause 1, characterized in that the compound ? ^ a -,! -, - ,. ¡, »- * - > . It can be stretched to at least 250% of the initial length in the first direction.

4. The absorbent compound as claimed in clause 1, characterized in that the composite can be stretched only at least 125% of the initial length in the second direction.

5. The absorbent compound as claimed in clause 1, characterized in that the composite can be stretched only at least 110% of the initial length in the second direction.

6. The absorbent composite as claimed in clause 1, characterized in that the substrate comprises a narrowed and bonded laminate of a layer of non-woven web and an elastic layer.

7. The absorbent composite as claimed in clause 6, characterized in that the non-woven web comprises a spunbond fabric.

8. The absorbent composite as claimed in clause 6, characterized in that the non-woven non-woven fabric comprises a meltblown fabric.

9. The absorbent composite as claimed in clause 6, characterized in that the non-woven web comprises a carded and bonded fabric.

10. The absorbent compound as claimed in clause 6, characterized in that the elastic layer comprises an elastic film.

11. The absorbent compound as claimed in clause 1, characterized in that the bags are spaced apart by distances of about 1.3-38 millimeters from one another when the compound is not subjected to a stretching force.

12. The absorbent compound as claimed in clause 1, characterized in that the bags are spaced apart at distances of about 2.5-25 millimeters when the composite is not subjected to a stretching force.

13. The absorbent compound as claimed in clause 1, characterized in that the bags are spaced apart at distances of about 3.8-13 millimeters when the composite is not subjected to a stretching force.

14. The absorbent compound as claimed in clause 1, characterized in that the bags have diameters of about 5.1-25 millimeters and depths of at least about 2.5 millimeters, when the composite is not subjected to a stretching force.

15. The absorbent compound as claimed in clause 1, characterized in that the bags have diameters of about 6.4-19.1 millimeters and depths of at least about 3.8-13 millimeters, when the composite is not subjected to a stretching force .

16. A disposable absorbent article comprising a liquid permeable topsheet, a bottom sheet essentially impermeable to liquid, and an absorbent composite between the topsheet and the topsheet; the absorbent composite comprises a selectively stretchable substrate which can be stretched to a greater extent in a first direction and to a lesser extent in a second direction perpendicular to the first direction;The absorbent composite further includes a plurality of bags in or near the substrate material, and a superabsorbent material in the bags.

17. The disposable absorbent article as claimed in clause 16, characterized in that it comprises a diaper, wherein the first direction is a lateral direction that extends between the leg openings on a wearer.

18. The disposable absorbent garment as claimed in clause 16, characterized in that the absorbent composite can be stretched to at least 150% of an initial length in a first direction and only less than 150% of an initial length in a second direction perpendicular to the first direction.

19. The disposable absorbent article as claimed in clause 16, characterized in that the absorbent composite can be stretched to at least 200% of an initial length in a first direction, and only to less than 125% of an initial length in a second direction perpendicular to the first direction.

20. The disposable absorbent article as claimed in clause 16, characterized in that the absorbent composite can be stretched to at least 250% of an initial length in a first direction, and only to less than 110% of an initial length in a second direction perpendicular to the first direction. ; Ú ?? ái ?? t n .i¿

21. The disposable absorbent article as claimed in clause 16, characterized in that the substrate comprises a narrowed and bonded laminate of a non-woven web and an elastic film.

22. The disposable absorbent article as claimed in clause 16, characterized in that the bags comprise together about 1-100 grams of the superabsorbent.

23. The disposable absorbent article as claimed in clause 16, characterized in that the bags together comprise about 3-50 grams of the superabsorbent. /

24. The disposable absorbent article as claimed in clause 16, characterized in that the bags together comprise about 5-15 grams of the superabsorbent.

25. The disposable absorbent article as claimed in clause 16, characterized in that the selectively stretchable substrate comprises the liquid permeable topsheet.

26. The disposable absorbent article as claimed in clause 16, characterized in that the .- n-n? »? .ftl? -? i ^ i,; and., ji .. The selectively stretchable sleeve comprises the lower sheet essentially impermeable to liquid.

27. An absorbent article, comprising a liquid-permeable top sheet, a bottom sheet essentially impermeable to liquid, and an absorbent composite between the top sheet and the bottom sheet; the absorbent composite includes a narrowed and bonded laminate of a non-woven web and an elastic film; The absorbent composite further includes a plurality of bags in or on the tapered and bonded laminate and the superabsorbent material in the bags.

28. The absorbent article as claimed in clause 27, characterized in that it comprises a diaper.

29. The absorbent article as claimed in clause 27, characterized in that it comprises a training underpants.

30. The absorbent article as claimed in clause 27, characterized in that it comprises an adult incontinence garment.

31. The absorbent article as claimed in clause 27, characterized in that it comprises swimwear.

32. The absorbent article as claimed in clause 27, characterized in that it comprises an absorbent article for personal care.

33. The absorbent article as claimed in clause 27, characterized in that it comprises a medical absorbent article. ^ ¿¿. ,. ^^. ^ i ^ ÉÜ ^ .l * jU *? . + **** i £. * a?.? SUMMARY An absorbent article that includes a liquid-permeable top sheet, a bottom sheet preferably permeable to water vapor and substantially impermeable to liquid and a selectively stretchable absorbent composite between the top sheet and the bottom sheet. The selectively stretchable absorbent composite is more stretchable in a first direction than in a second direction perpendicular to the first direction, and can be stretched to at least 150% of an initial length in the first direction. The first composite includes a selectively stretchable substrate layer and a plurality of bags in or on the substrate layer. The bags each contain a quantity of superabsorbent material, which can swell when exposed to a liquid insult. When the substrate is stretched, the bags are also spaced apart, thus promoting comfort and lightened gel blockage caused by adjacent bags that swell.